1. Field of the Invention
The present invention relates to a paint apparatus for automatically painting a workpiece conveyed into a painting booth by a conveyor using two painting robots which are prevented from interfering with each other.
2. Description of the Prior Art
Painting automobile bumpers is an automated process in which the bumpers are usually painted using painting robots. A painting line is provided with a plurality of painting robots to increase production efficiency.
FIG. 12 illustrates one example of a conventional automobile bumper painting line. A conveyor 2 extends through a painting booth 1 and automobile bumpers 3 are conveyed into the painting booth 1 at regular intervals. The bumpers 3 are stopped at four predetermined painting positions to be painted. Painting robots 4 are arranged adjacent to respective painting positions. The respective painting robots 4 paint the respective, hatched portions of the bumpers 3.
FIG. 13 illustrates another example of a conventional bumper painting line which is shortened as compared with the painting line of FIG. 12. In the painting line of FIG. 13, a conveyor 12 extends through a painting booth 11 where two predetermined painting positions are provided. End portions of a bumper 13 are painted at a first painting position using two first painting robots and the remaining portion of the bumper 13 is painted at a second painting position using two second painting robots. By arranging the two first robots and the two second robots in an opposing relationship with each other, the length of the painting booth 11 is shortened.
However, in this opposing arrangement of the painting robots, the following problems result:
First, because painting programs of the opposing robots are executed independently of each other, there is an overlapping zone in the working areas of the opposing robots. As a result, the opposing robots may collide with each other in the overlapping zone as shown in FIG. 14. To prevent such a collision requires complicated and difficult programming.
Second, the opposing robots spray large amounts of paint onto each other. When the sprayed paint falls from the robots onto a bumper positioned under the robots, the paint quality of the bumper is deteriorated.